SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35c8b1eb352a4a3dfb3de7c06398cd58dbd38131d9fbc0b49c55e9a75cca3dcc' 
  AND token = '2p7915nNSj2b3crxilDppIYCzwD0/0v1e+ncHU/55rU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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