SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd135ac2eb55baf4366c62717859893e247f70a374d6c02134ef3084594690f37' 
  AND token = 'AMd8TJ1xVnPwpFCp2Tt4iaJuCQnDYdoIVAHBGnoPa6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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