SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bb38954497be0aefb2712353bbc6bcc8e487ad75fa65ee048cce4df339b7fe4' 
  AND token = 'FmoFUOP51ND0unbEr1aynWuazzBQchRjayFQAP5pOZw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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