SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6176c2174198147f0ddb6509cf385b2fbf116e8ab77df11a1588dc107ffe980' 
  AND token = 'gwMosu60wiNJmJmMb1HKDe+UVcl4kgJCnbT5t48SKuU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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