SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9af14388737760239c97e71f7adf290e5feb93ed261d20fc08f800561674a302' 
  AND token = '7JFmEpiNr592MKnciAMnEOZSorn2GGedKQnzOOaFORY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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