SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e5e5d72d412818e507735b98e5a75492e275e990163271a85c4d8c0720e4651' 
  AND token = 'Hd3GxIFDVtQry1NXunkls12AEmgdSfPGz9IaJTrVUt4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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