SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2dcfa5a928351f88370a4b173636fca6e85932017f57f1172e1808859bbdcd02' 
  AND token = '6A29nhzdCQfoF4jwogmn1ngwIVFaNAAtnwbebiRG14s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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