SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '594f03dea0f83dd87cb665a2d7903c9d78536ccf90cb35bbd9a00040d72d435d' 
  AND token = 'fn10eQmQxdB0D865ANBL3mAOCb7wr21XqsMnZpPY7JQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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