SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcda06e422d41c9e49ba9ecb104242adda43874d8b16bdfc13266fe04af8e80f' 
  AND token = 'luGDPNkJKo9VcCJuP/2+oDU8L4WqYVyn1iHBGxZlO/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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