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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3708a931e73bc40327a2247ee43761e9e7e598de18c0f40f7ca453e1113eef9' 
  AND token = 'kznESNM8xpn4AQNkxfO6865Bhni432eTjJ3Q8lOVQIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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