SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c051e8a733d58beb5576f1d1a94f59d0e8daad6afffb86f847d0a600d9e6ad09' 
  AND token = 'B5SMp+WBld8RgJsAIhly0Za9Jsdq+sVlD5IreS29n04=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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