SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad25a2afcc1966ecf68185ad81973f5b76378ecfbc3bf6ac62389049572f0cc2' 
  AND token = 'sxb1KQsWRVRoQV0mvENxS8N0kvl1wxGPQCnKxAHop6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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