SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b815bdafd436156685ab938206ac7952d1c6b93e0643f9e0a8bec6d8f7f55f2a' 
  AND token = '0levdqsaV0e0KSHdGOS9W+jkl/UWEzowHaJcbEbU+UQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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