SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df1af19dfff25cb2cb6b3856075e98d5993f739ce244887fc85ae6c6fa9fe444' 
  AND token = '8rFOviYen+YBRUlwZOt+hS2gzm44bhHFCoE3Pw/GjzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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