SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c3762491e0c940b7c68e6a6212d82fcb9af449eb3843136cb9fe38ef4104a03' 
  AND token = '2t6VHzwXV8j+yKAgTglgP0lD3HF3vBJFP0H1qZlySjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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