SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c4750178456e1954d4507a519b5deff4899bf9032563d7883fd89edace3bf61' 
  AND token = 'Rk4D6foL+0aDq6RNT5Rf5oFULj7rLwpOmGY8pba0R20=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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