SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de4d136aa9d0cf450879fb00d17d59942ca8573723ff5fa6e8242f84727da2d1' 
  AND token = 'SlDroGgIIkAl7n/7+eCJIz+X0FmdBV3sG5MakUlxUPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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