SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '239701b962318b5bdc395505a2695c3353b7cf8ef6e6f1d637dbdd08a7c6dc60' 
  AND token = '8FE5wg/0wxMWb9iKNfU9fPk3Xupo+PYRR6ReWAFCE1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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