SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85ec7360532b0be282cc9abf04e6ca444bc3d44f81ebab617233963d92cd4c6a' 
  AND token = 'AU7rmtoLnwKHPHZ6gFPQHXtK4xSuLve+wwKB1h1nVmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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