SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '4c5da1b802c5e4672f10abad89a60a45318f850f1682be2e0e9c46cd9c3f8fe3' 
  AND token = 'YwsyWtXYmEm5gEeTQuLH5p2pcgF5RNdZ2P/JJY8Mw6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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