SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6257d67f6f2cfafe8cc452f858817599287398cc921ce2bc2067b9e7201441f' 
  AND token = 'notxdE33dWmristUQtzIEFNo86vclsMROnS7pttkxQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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