SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e52290b3accba6fa674416bd1efeba022b5c2911fe5fd63cc154b3031a042f46' 
  AND token = 'iiPMDigiI70K9cw53ZwVwHWBY9yIm2Pfs7huz+mImd0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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