SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6836138e8da2779db87131124de17f1c8549a0c736ef274bccf91c2f2815cb87' 
  AND token = 'CkJ1HsobalyFhKnbh8V/UrvILGSuB3yAjp4tV/lWrxM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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