SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5375a883dd9d8551b9aa1ecb7faa7660727eb08bb1c1041a07c860449a93542' 
  AND token = 'LuG2v38wAXWxY+FJonGKMWrAfBUg4xIVtIV20lsSzPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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