SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3bedf705e4490ca888053aeedfb2b5adc0908108252d0129a7984da2a8abc14' 
  AND token = 'Y/Tov28reBWMOTqp3ApVsSkZeYiJtut5jfAwNZpM6Pw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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