SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8ee3baa66cda4c4d746ea2dc62628bfb82f2371a3a4f9f58b3adb972eb6ad94' 
  AND token = 'UNLK3H/Wb3dNvv8fgNHL+w1+3LSYLSp2a3vwNZSE11M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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