SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b72bedf3a1241535088eabadbbc2a989f5b5dc0aa5698e864c24a1b9d5a6b337' 
  AND token = 'rSI8cvsOB5nBrfx87wqi6IfTHwOfhsBsQzpZNarLcWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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