SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '305678102b71922a1b1648dbbe48f9c042bbb50426fa2acb32fe7bcd5df162df' 
  AND token = 'thr2EKpiachVcsYVGuBhwQxv9HT9PPqJcK4NVJK5UVU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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