SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b926c3ad5f320d4f168a432ea5589ea20a73801f8c6f6195cea86551aa2eca3d' 
  AND token = 'Gs5N1khxWrxcp2xQpsUDufdmyeLpz7MtX/GSldprMJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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