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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '399e19a18812fa45cfad29cd531430e102ff0f31316d2cd6c52490c83c142b69' 
  AND token = '420TBG588xCVl0ouGfz5qP9C1usXui8Si7Dj6eMXwPA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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