SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3584f971f8791e1449032aac2c60e63008112b771f4c97a58a105676033b5b41' 
  AND token = 'Lj9zVefpJAAC3V+3oH6jNKisV+CBJMR1BvzOZjnuWOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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