SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b38eed00a876413855cd219c35ed173496f3a64b740b06bd9fb73cfd922f31ad' 
  AND token = 'fJ/vGHZBDEsJtR1Zdf7oChtuj4ci0G4kAjg8VmPldSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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