SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbbd421db86b8a446deb5911b10bd08a889512547f9f22f94944ced731bc31e5' 
  AND token = 'ujHIUkjJTMkRzFP8Jxc88++OeiAa/ea3o0mV4hMEvCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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