SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcbf8888102a37ce97aac4dfa8c9ab76136d43cfc5d0810462fd7d78b6ba804a' 
  AND token = 'QwHeytBP+xVcrIEw5u5EBLj2Sgjs7ntLL2HyWQxguSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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