SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efe54d0950d8558369dabdd9a8023fedc880a50d6bb582a03d47b8484ab399a4' 
  AND token = 'Dkok66n05K37ZUJzw2EuvW0Rt1UteUldz3TdIIhlwrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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