SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a93aeece7227a97ee123e421b3b3b40d7be5913ce26a7178e28382607765a2cf' 
  AND token = 'abIP/WdyDjPzbCRd16uJIXsJUOaLY2EcwtcHAb0pBk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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