SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a86187f024c6309e1fbce6bde4cb3e54da04261620d05e05aedb3cf5217ebea' 
  AND token = 'cUqJiZ1gEte1guD4zKHagomSqn5UtbrS1I3Ip0hbxko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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