SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd7f6e60f0d378f4532c593c889591a1c7f532aa000f55c091b5bf3d35422be2' 
  AND token = '6aaYWHjCCWzcNYWDmXTgraeYA4XFIn2nzyUlaXwc0J0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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