SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ef7c401794bf1464b27d6164e4c70361c37d987720179783858724b094859b8' 
  AND token = 'mRmVGHci68ruUxJJGvFbI0SRx+uIccHgXYlev4gqSYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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