SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca777518367f6708b825e55cd4df02ff7333214dd280eff39b61256d601793c8' 
  AND token = 'WxNGw2DHvPQ3ltzYxDJDycMAzzl02EPkPrfNt3B+Sss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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