SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cac66ee8fe4c38d59f19ced38555aa42e4166a6e486943dad15b3e0c7abf627' 
  AND token = 'kY4HIappWqLL7cvPiy4cXFh95M94m83dgpzpCdGfuhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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