SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48ff18717f21659a4e3358b556f4321351eb3dc668a3313d9538b8366683a19a' 
  AND token = 'LwApzfSTquJc1+5aKciZOCujMttYx4He3mr6VPwWJzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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