SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6293ae0c76695b2538d19090c68e4ea67839cb16e9a445a5cb093e2299cd5421' 
  AND token = 'zkzuqYUBiIbhGU3ovTul4L7x+r/85iEWhLHZtAB/uEY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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