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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6704ccd8bc4c84a5d6f522b429bc47d447d53a36ec0cebfa6bcf6ecd6328ecb0' 
  AND token = '00X8xDeYSF3MycgYB4v0CNAtuALBCEZRAnk67ET18Rw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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