SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bc376e60ace12cd4a95c81379b182798c76c66cc7a032ca23d0666180d21a54' 
  AND token = 'UQGH/RT102QI0LFEhNlDdqYrOsn6PCZGKBmQlubkFI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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