SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf52f3ff2d670db673d74992e5e8a9720cbfa8fefd76d6542f4123df18e06551' 
  AND token = 'NEOVyAfcHVxxhhB5WNu6WcgyRSem0T7NvuvBDeStiu4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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