SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '700dfabcae6ec59f4fbb0bcc3b4a570308bd3eaa6c449cd4d73994debc847634' 
  AND token = 'gNaDAt7FT7Av7tL7WW6m80mxLe3I3tgTA2hpFSG3hU4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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