SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '546e9e7cd8b4de0a28963d990b6685cad8782715928e851393b8f6781166fee0' 
  AND token = 'dxOhTfYUVRtFeUvuzQAOArAFjG3nLwdc8D/XcIyfrt4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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