SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e5c85b12ed0299a465a4ea1fd8c302d9ec2a20393176248742dca8781f8bbb3' 
  AND token = '7Otfj6rAq2oqNBetdWTNW9qifte8DElT2xCTL3XgB6s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}