SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b480cfe781dd33717cc5ef5d1ab5cc6b84d687bc7edace56811332cf5e7ce9a' 
  AND token = 'nr9Cs5/oaIwiFEhIvqVZtfKuVa5/wTLFo+HjBqHQFGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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