SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '235a7dd4706cd86f392ed2b66b67d8fc961352596b99f1f7c0b94e00876ac3cc' 
  AND token = '0+rmggv2KMprYtlEGMm7mhzZSkalUqil3QyH0/w1Wbo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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