SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '779baa9384d63b84c842711f067d8a62b9b7ac21307ea272078911259712c0ae' 
  AND token = 'LOfXgC2MAcWNZGMgA75llIxCccviTBo7Kv0HuPZblNg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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