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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3f684c19a1732bb23fbb20325916b26dc23cb98384d05ef5cf4e75ed59c5217' 
  AND token = 'PWan4Vv0EoXLnzv3la/yPeZqTXxByA7Wj/RJafXK/fc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}