SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a51ef58a0cf1ebd8b4a31f891e0dfa508be9b6523cba99c881530387031a46d2' 
  AND token = 'dLyQAfsEvgmlJg5Q6isPYiMWyHMOBfIL7+VG7pSS5IM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}