SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7cf7c3cfce098a67640de1e69476e1f59fa2454d5b717936d7baa94e586d819f' 
  AND token = 'u40mVXgAMN9lmAzyxsX/dTyGWVC/Prv7ljp3BZiWUnU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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