SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28474c630448a306a06dd8515bda45bf314db15e617da69b1bf3c25df5155832' 
  AND token = 'K7SZHQbVAJDoAowI5dndx/3ocjWGq1vyvoyFeY2wVvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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