SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '804c5a97560d661b3e1479e22c80a2f66c5db1d56bd99fee71af06399689dd56' 
  AND token = 'hPdDoHCOSJbmuHKlpJfh6CkoW6/+t/GbvdBom6XZMz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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