SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e1c1dd761aa9edda1f44091f09755c2878957923a3acbfed03fe4088313e705' 
  AND token = '4eHv5ppvPlVwq3kp3ZcWlSXj/YEVK92QfVBWvwkG5Hw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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