SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '41ce0425bf2fefe89ccde47ace6fd449b129281da790baf50bd6c2f21afd3fd9' 
  AND token = '9tjJtYZkxzY9LPYDWkt4G+fKVOHDVRtQI1rAcPZpMlU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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