SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44b3dfcc86832aba23aa7d22787bdb8d06065da70e73734a3443e44024e92d0f' 
  AND token = 'qEnteB4UA7z4xySVDJwvWlrPZwmMFMGwWeIGK2y2fRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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