SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd3534720f016ad1b785f79ec2408349389981b8af800b298c49585e276a9b06' 
  AND token = 'sKKXs1xeIE5eOG2skNjKcFhEsN5Vo+aelgELEhpnnd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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