SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '249a44be89326d4e80c185953745d2796501a8f499e4a7d1b7b139ccb29f3b31' 
  AND token = 'KYXonqJ5WmX1h1fO0AIQzbLF2BhwyH1QacY+gy0AZNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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