SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '10ea4851c2451848369a54f283d97e42d59d45be02285b044152a3770546381f' 
  AND token = 'n1t0jwg/vpHE+JWzExvc/jow+lIqdAlUhgtxrb+aFjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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