SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f98841957c563848057e18d03ce5f392f94d7e91681ccf98f6cbfad262c794cd' 
  AND token = 'QUnEQ/CE7kUlB64VTw7ObJtw7rWlp3MpcWtWWzWQTQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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