SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ab58732bf5a201b97741a166e1904dc90e00a324d1ed3dcc691963185ade7ac' 
  AND token = 'KWYMUp0+KzD+brGPp3zQbnKXmKSqZoBoW+JqB2t0YPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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