SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac3989b45a10d05aaef220437c737e6af09ef1f54d6400bd2267c8235e66e098' 
  AND token = 'WU8a0JBbKWAaR/96acv9Wcdc0BOlmK0SYo4btyAbZc8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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