SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99ec03973e8d537a6b9489d7591f99fbc604f6879b94e3defd14c1768607d274' 
  AND token = 'aqsxoBcHJXu1jGAx70wNMmon3bVbIlYSPfKZ8pHhnRU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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