SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ffc2cb0a9bbbf13f4dbf362539c120bc929ae0e449656ee7f3b3c072d8fcf81' 
  AND token = 'Np9pChPSBoDgpIeWOo1hgBYkTjQN9g140TQguy9Xz+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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