SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff4b5bda821beaf5821405810b72599e7dc17e3bb9eb65ef4f1ab483071c4629' 
  AND token = 'w0Qwrwnry70cauHlffJItadE+Je7uWIyEBydk9r4J8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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