SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '773a6012a49f00a5cd2b46fe49d97d451b751101cccee330bf4add4968835117' 
  AND token = 'n5zRAAs+89PMlrzGVUz2uFwyjKKCf6BAUP47YyrJdCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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