SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a83e6ffbfb76a1f62a24e626e91451805c4d28d57090a9815ce94ffe733df7f9' 
  AND token = 'j0Bf/8jQxNDtgCdzEUhRNVUw/bAMujZ6N4K0NEgxHRY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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