SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe20c273c7987052efa0cc8075324c79a5655e59ff27695bad5ae9014a69c549' 
  AND token = 'IRYOHkg2p5n1Zqt4iEcTe9P/YJATeVjBnDRJ7XOLgN4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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