SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5782031ca39f98953a9757e2532b9d7f3eb076db3940a9c4f9da352f414964a2' 
  AND token = '/gN+N62BPfuKgVLRqq6VL0GptJPucvEAEIWcwoI6dn8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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