SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c73d329f3453f57f03fb5807e5604010884620fa2ddfd736664ed37d2ae33e5' 
  AND token = 'lxaUAlT3oqISLIoLtRMsl1NOBjhXRJkElRL7p7G0lCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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