SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0818b3cb119f71c67610226277697e1028822f0b5b3dfec5011200dacbff4187' 
  AND token = 'QpzlDteuiVp4sGqvsgXrZ55+ZS01Dqh12HTvK0PwlSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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