SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a0e8663314e1789cd712017e6a768eac38f3830882e938c2ba8a1f861f6d3a8' 
  AND token = 'LnlI3AICt1bRt6FhOWcAORnL+/y/Ypaad7uFMeGw5oE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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