SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '511966f270867e218749284a25dd54d233d64bfa47a7924c730b3e25b4b54ac9' 
  AND token = '3Y6IIrOGEv+ZySNHO06+NrA9jJhZ++CGalPUC41BXb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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